Method and apparatus for picture transmission



Oct. 30, 1928.

A. WEAVER METHOD AND APPARATUS FOR PICTURE TRANSMISSION Filed Dec. 15, 1923 IN VE N TOR J fl aver A TTOPNEY Patented Oct. 30,1928.

' UNITED STATES PATENT OFFICE.

ALLAN WEAVER, OF IBROOKLYN, NEW YORK, ASSTGNOR TO AIMERICJAN TELEPHONE AND TELEGRAPH COMPANY, A CORPORATION OF NEW YOEK.

I METHOD AND ArrAEA'rus'roR rIcrunE TEANsMIssroN;

Application filed December 15, 1923. Serial No. 681,001.

I other object of my invention is to provide a sure relates to these the invention.

picture or image transmitting system having a new and improved means for produc.

ing the image at the receiving end. Another object of my invention involves determining the degrees of light and shade in the received picture or image by the amplitude of vibration of a receiving element or stylus. These and various objects'of my invention will become more readily apparent on con sidera-.

'tion of a limited number of specific examples which I have chosen to illustrate in the accompanying drawings and describe in the following specification. It will be understood that the invention is defined in the appended claims and that the following discloparticular examples of Referring to the drawings, Figure 1 is a diagram illustratingmn embodiment of my invention; Fig. 1 is a detailof Fig. 1 looking at the transmitting drum at a right angle to its axis instead of along its axis as in Fig. 1; Fig. 2 is an enlarged detail which will be referred to in explaining the opera tion of the recording stylus; Fig. 3 is a detail modification; and Fig. 4 is a detail show ing the character of; the record made when the modification of Fig. 3 is employed.

The picture to be transmitted is assumed to be put in the form of a relief film which is wrapped on the drum 10. This drum 10 is rotated uniformly and advanced relatively slowly along its axis meanwhile, so that the stylus 9 in engagement therewith traces a helical path of small pitch on the film.

Due to-the varying relief of the film, the stylus 9 is vibrated and actuates the microphone transmitter 11 to modulate the alternating current from the oscillator 12. This current is amplified by the amplifier 13 and put on the line 14.

At the receiving end the received current oes through a transformer 15 to an ampliidler 16 and thence to the winding 17 about the magnetic reed 18 between the forked poles 19 of the magnet 25. The members 20 are of non-magnetic material.

It will be understood that the current transmitted and receivedis a carrier current of frequency determined by the oscillator 12 and of amplitude corresponding to the lights and shades of the picture as determined by the microphone 11. The reed 18 is designed to be aperiodic, and accordingly it is vibrated with a frequency the same as the carrier frequency and with an amplitude corresponding to the amplitude of the transmitted current.

A place of high relief in the film on the drum 10 causes high pressure and reduced resistance in the microphone 11. This means that the current applied to the amplifier 13 is of high amplitude, and the result at the receiving end is that the armature 18 vibrates with wide amplitude. High relief in the film at the transmitting end corresponds to a wide amplitude of the vibrating armature 18, and vice versa.

At the receiving end the shaft 24 carries a drum 23 which is rotated and traversed 'in synchronism with the drum 10 at the transmitting end. One method by which the drums may be synchronized is disclosed in British Patent 242,694, granted February 1, 1926. The armature 18 carries an extension 21 with a stylus 22 which is adapted to mark on a suitable picture receiving member till stylus'21 will vibratewith such a small amplitude as to record lines 31 which appear to be merely straight lines. But as the transmitting stylus passes over the relief ridges 30, the amplitude of the transmitted current will be greatly increasethand the receiving stylus Wlll then vibrate Widely as at 27 in direction perpendicular to the surface of the receiving platen instead of along that surface as in Fig. 1.- When the amplitude of the vibration of the receiving stylus is narrow, light. lines are traced as at 31 in Fig. i, but when the amplitude of vibration is wide the carbon copying paper is pressed down more, and a darker shade is obtained as at 27 in Fig. 4.

I claim:

1. A member having a picture receiving surface, a stylus in engagement therewith,

means to traverse the said member relatively to the stylus, means to produce a sustained alternating carrier current, means to modulate said carrier current with respect to its amplitude, means to transmit said carrier current modulated corresponding to a picture to be transmitted, and means to apply the received modulated carrier current to vibrate the stylus in correspondence with the received carrier current. V

2. A member having a picture receiving surface, a stylus in engagement therewith, means to traverse the said member relatively to the stylus, means to produce an alternating carrier current ofa definite frequency, means to modulate said carrier current means to transmit said carrier current modulated corresponding to a picture to be transmitted, and means to apply the received current to vibrate the stylus at the frequency of and with an amplitude corresponding to the received carrier current whereby a heavier record is made with increased amplitude of vibration thus reproducing the lights and shades of the picture to be transmitted.

The method of transmitting and receiving apicture which involves producing a carrier current of a definite frequency, modulating said carrier current according to picture characteristics, vibrating a receiving stylus at the frequency of and with an amplitude corresponding to said carrier current modulated according to the picture characteristics and causing said stylus by its engagemen with a picture receiving surface to reproduce the lights and shades of the picture in accordance with the amplitude of vibration. l

The method of receiving a modulated picture transmitting carrier current of a definite frequency which consists in applying said current to vibrate a stylus in proportion to the amplitude of the said carrier current, and traversing a picture receiving member under said stylus whereby the light shades will cause the stylus to record thin lines and the dark shades will cause ,it to vibrate widely and make the recorded lines effectively heavier.

5. The method of receiving a modulated picture transmitting carrier current of a definite frequency which consists in applying said current to vibrate a stylus in proportion to the amplitude of the said carrier current and at the frequency of said carrier current, and passing a picture receiving member un der said stylus in successive parallel traverses transverse to the direction of vibration of the stylus, so that the stylus will trace lines of degree of shade corresponding to the amplitude of vibration.

6. In combination, a picture receiving member, a stylus in engagement therewith, and means to vibrate said stylus at the same rate as a received earriercurrent whose amplitude is modulated in accordance with the characteristics of the picture to be received.

7. In combination, a picture receiving member, a drum carrying said member and rotating on its axis and traversing slowly lengthwise, a stylus engaging said member, and means to vibrate said stylus parallel to the drum axis in accordance with a received picture transmitting carrier current the amplitude of which is modulated in accordance with the characteristics of the picture to be received.

8. In a picture transmission system, a line, a member having a picture receiving surface, a stylus in engagement therewith, means for. moving said member transversely with regard to the stylus, means for generating carrier current, means for modulating the amplitude of said carrier current in accordance with the picture characteristics, means for applying the modulated current to the line, means for receiving the modulated current, and means for applying the received modulated carrier current to vibrate the stylus in accordance with the picture characteristics.

9. In an electromechanical image producing system, a stylus in engagement with the surface on which the image is to be recorded, means for transmitting a sustained carrier current the amplitude of thepulsations of which is continuously varied in accordance with tone values of successive elemental areas of the picture or object an image of which is he produced, and means for applying said continuously varied carrier current to vibrate said stylus thereby producing said image.

16. Jlfeans for producing object the tone values of the elemental .1

range of t ue values, comprising the 'transini ter for modulating a carrier current, and image producing means at the re cei to ..-.nsl ate said currents uniform undulatory lines which, viewed at a distance, the direction of said lines in accordance with appear as tone values corresponding to those tone values of elemental areas of the picture of elemental areas of the object. or object an image of which isto be produced. 1

11. An electromechanical image producing In testimony whereof, I have signed m 5 system comprising means for recording a name to this specification this 13th day of fixed number of lines per unit area of the December 1923. image, and means for causing variations in ALLAN WEAVER. 

